This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A378645 #7 Dec 03 2024 19:50:05
%S A378645 1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,3,-1,-1,-1,-1,-1,3,-1,1,-1,-1,-1,3,
%T A378645 -1,-1,-1,-1,-1,11,-1,-1,-1,-1,-1,-1,-1,-1,-1,5,-1,11,-1,-1,-1,-1,-1,
%U A378645 3,-1,-1,-1,-1,-1,-1,-1,7,-1,-1,-1,-3,-1,-1,-1,-1,-1,11,-1,-1,-1,3,-1,-1,-1,-1,-1,-1,-1,11,-1,5,-1,-1,-1,3
%N A378645 Dirichlet convolution of A055615 and A103977.
%H A378645 Antti Karttunen, <a href="/A378645/b378645.txt">Table of n, a(n) for n = 1..20000</a>
%F A378645 a(n) = Sum_{d|n} A055615(d)*A103977(n/d).
%F A378645 a(n) = A153881(n) always when n is a non-abundant number (A263837), and also for some of the abundant numbers, A005101.
%o A378645 (PARI)
%o A378645 A055615(n) = (n*moebius(n));
%o A378645 A378645(n) = sumdiv(n,d,A055615(d)*A103977(n/d));
%Y A378645 Cf. A055615, A263837, A103977, A153881, A378646 (Dirichlet inverse).
%K A378645 sign
%O A378645 1,12
%A A378645 _Antti Karttunen_, Dec 03 2024